1. Technical Field
The present invention relates to an actuator, an optical scanner, and an image forming apparatus.
2. Related Art
Actuators that use torsional vibrators are known (for example, see JP-A-2010-79243).
For example, in JP-A-2010-79243, a light deflector is disclosed in which a movable plate (movable portion), a support frame (support portion), and one pair of elastic support portions (connection portions) that support the movable plate so as to be able to revolve torsionally (twist) with respect to the support frame are provided, and each elastic support portion is configured by two posts (beam members).
The movable plate, support frame, and one pair of the elastic support portions are integrally formed by performing anisotropic etching of a silicon substrate of which the principal face is configured by a plane (100) formed from silicon.
In addition, in the light deflector according to JP-A-2010-79243, the movable plate forms an octagon in a plan view. Thus, the movable plate has a decreased weight at a position located far from the revolving axis (oscillation axis), which advantageously decreases the moment of inertia.
However, in a case where the movable plate having an octagon shape in a plan view is manufactured through anisotropic etching as described above, there is a large variation in the shape due to the relation with crystal planes.